Male hypogonadism is a common hormone deficiency in men that involves decreased functional activity of the gonads. Male hypogonadism results from a variety of conditions in which testosterone concentration is diminished below the normal range. The hypogonadic condition is sometimes linked with a number of physiological changes, such as diminished interest in sex, impotence, reduced lean body mass, decreased bone density, affected mood, and reduced energy levels.
In the United States, men of all ages are treated for hypogonadism using testosterone replacement therapy. Various methods of delivering testosterone have been considered and developed to provide suitable replacement therapies. Examples include intramuscular injections, pellet implants, transdermal patches, and hydroalcoholic testosterone gels. Commercial testosterone gels include AndroGel® testosterone gel from AbbVie, Inc., and Testim® testosterone gel from Auxilium, each of which is a one-percent testosterone gel that is administered by application of the gel to external skin surfaces whereafter testosterone in the gel passes through the skin. AndroGel® is also commercially available in a 1.62-percent testosterone gel product.
A testosterone gel is a medicinal formulation that can be applied externally to a patient's skin and delivers testosterone transdermally. These gels are designed to provide a combination of useful rheological, tactile, and functional (testosterone delivery) properties, preferably including desired pharmaceutical stability, and without undesirable odor, texture, or appearance. Rheological properties such as gel viscosity should allow a gel to be applied externally to skin and thereafter remain at that location of application for a period of uptake of the testosterone through the skin. Tactile properties relate to the feel and texture of the gel when touched and applied by a user, with preferred gels exhibiting a smooth feel. Good delivery properties (e.g., uptake) allow an effective amount of testosterone from the applied gel to be absorbed through skin during the time that the gel remains located at the skin surface.
Certain specific ingredients are included in commercial testosterone gel products to achieve desired properties of viscosity and uptake, such as enhancers, that is, a material which is capable of increasing the rate of passage of an androgen through a body membrane. For example, Testim® testosterone gel includes the chemically complex, cyclic oxacyclohexadecane-2-one.
Doctors and patients continue to need improved testosterone gel products having good stability, cosmetic properties, and efficacy, especially such products that also benefit from cost advantages or improved performance relative to current available product options.